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Full-Text Articles in Physical Sciences and Mathematics
Time-Series Photometric Spot Modeling. Iii. Thirty Years In The Life Of Hk Lacertae., Katalin Oláh, Zsolt Kővári, János Bartus, Klaus G. Strassmeier, Douglas S. Hall, Gregory W. Henry
Time-Series Photometric Spot Modeling. Iii. Thirty Years In The Life Of Hk Lacertae., Katalin Oláh, Zsolt Kővári, János Bartus, Klaus G. Strassmeier, Douglas S. Hall, Gregory W. Henry
Information Systems and Engineering Management Research Publications
We present a spot modeling analysis of the active late-type giant HK Lac using 30 years of photometry, including 600 new data points from the last six years. We have analyzed folded light curves and, when we had long continuous data sets, applied a new computer code for time-series modeling. The validity of the modeling results was tested as a function of the photometric noise. We have determined the unspotted brightness of HK Lac in the BV(RI)_C_ bandpasses and obtained a spot temperature of {DELTA}T=1200+/-100K. Polar active regions were recovered throughout the modeling because no other scenario was able to …
The Extremely Active Single Giant 1e 1751+7046 = Et Draconis: Revised Properties And A Reevaluation Of Its Evolutionary Status, Carol W. Ambruster, Francis C. Fekel, Edward F. Guinan, Bruce J. Hrivnak
The Extremely Active Single Giant 1e 1751+7046 = Et Draconis: Revised Properties And A Reevaluation Of Its Evolutionary Status, Carol W. Ambruster, Francis C. Fekel, Edward F. Guinan, Bruce J. Hrivnak
Information Systems and Engineering Management Research Publications
New spectroscopic observations have resulted in significant revisions to several of the orginally published properties of the X-ray bright, chromospherically active star 1E 1751+7046: the spectral classification has been revised from K5 IV to K0 III, v sin i from 30-40 km s-1 to 23 km s-1, and the reported nondetection of the Li I 6707 Å line to a significant log epsilon(Li) = 1.8. Chromospheric and transition region surface fluxes from IUE observations and the coronal surface flux from earlier Einstein data are close to saturation levels, and comparable only to very active binaries, pre-main-sequence stars, and FK Comae …
Properties Of Sun-Like Stars With Planets: Ρ1 Cancri, Τ Bootis, And Υ Andromedae, Sallie L. Baliunas, Gregory W. Henry, Robert A. Donahue, Francis C. Fekel, Willie Soon
Properties Of Sun-Like Stars With Planets: Ρ1 Cancri, Τ Bootis, And Υ Andromedae, Sallie L. Baliunas, Gregory W. Henry, Robert A. Donahue, Francis C. Fekel, Willie Soon
Information Systems and Engineering Management Research Publications
Planets have been reported orbiting the Sun-like stars ρ1 Cnc, τ Boo, and υ And based on low-amplitude radial velocity variations. We have derived information on the first two stars from analysis of spectra, as well as parallel records of high-precision Strömgren b and y photometry and Ca II H + K fluxes. In the case of ρ1 Cnc, the upper limit (peak to peak) of nondetection of photometric variability at the orbital period is Δy ~ 0.0004 mag. The possibility of a planetary transit cannot be ruled out completely from the photometric data. Variations of the …